"How am I ever going to be able to move past this without constantly thinking now that he’s looking at other people or I’m not good enough, slim enough etc."
I honestly think you're focusing on completely the wrong thing - possibly as some form of avoidance, because dealing with the ACTUAL problem of your husband's behaviour is overwhelming you.
The problem is not that he's comparing you to other women - the problem is that he is a predatory sex pest. I'd be so disgusted with him right now that I'd struggle to even look at him. I certainly wouldn't give a flying fuck what he thought of me!
"I desperately need other people’s perspectives as my mental health has taken a battering and I’m struggling to know what to do."
I wonder if you've been avoiding acknowledging that your husband is a wrong 'un, sticking you fingers in your ears and singing la-la-la; and that has is what has impacted your mental health. At some level he set your radar pinging, and shoving it down into your subconscious has cost you dearly. In which case, your mental health will improve enormously when you take the blinkers off, see him for what he is, accept that disgust is a perfectly normal reaction, and set about divorcing him.
"This one girl at work has raised this all about him but there are witnesses to the comments. Apparently he’s quite touchy feely with her, only stuff like hand on shoulder when talking, brushing her hair away to look at her earring etc. But she obviously feels so uncomfortable to have brought it to this point."
I think you're desperately trying to victim blame here, as part of avoiding the reality of Your Husband The Sex Pest. "Only" is the giveaway. Can you, hand on heart, say you wouldn't be totally creeped out if a work colleague behaved like this to you? I would. So stop minimising what he's done - done repeatedly and for quite some time. This isn't a one-off mistake or misunderstanding - he has carried out a persistent and sustained sexual harassment, and he deserved the sack.
"He hasn’t cheated and I don’t believe he has or would!"
Is that your only measure of a good man? What he did was far worse, in my opinion. He put a woman in fear. I'd bet money he rather enjoyed feeling her fear, feeling the power of being able to make someone fearful. Do NOT minimise his actions or his intent.
What you need to deal with now is the practicalities. First, finances - he's been sacked, so his income is no more. Are you working? Can you manage on your salary? Have you savings to keep paying the bills? This is your priority, the roof over your head and the food on the table. Secondly, I'd ask him to move out, to give you a bit of headspace. You need time to process this because it is massive, and having him hanging around protesting 'it was nothing' will do nothing for your mental health. And once he's out, ponder long and hard what you want your future to be, and concentrate on that, not him.
((hug))